IR 05000293/1986017

Insp Rept 50-293/86-17 on 860412-0425.No Violation Noted. Major Areas Inspected:Spurious Group 1 Primary Containment Isolation on 860404 & 12 & Failure of MSIV to Reopen After Isolations

ML20205P914
Person / Time
Site:	Pilgrim
Issue date:	05/16/1986
From:	Kister H, Strosnider J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20205P911	List: IR 05000293/1986017 ML20205P906 ML20205P914
References
50-293-86-17, CAL-86-10, NUDOCS 8605280047
Preceding documents:	ML20207G266 (19 April 1986)
Download: ML20205P914 (44)

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.i . U. S. NUCLEAR REGULATORY COMMISSION AL'GMENTED INCIDENT RESPONSE TEAM Report No. 50-293/86-17 Docket No'. 50-293 Licensee: Boston Edison Company M/C Nuclear ATTN: Mr. William D. Harrington Senior Vice President, Nuclear 800 Boylston Street , Boston, Massachusetts 02199

Facility Name: Pilgrim Nuclear Power Station Inspection At: Plymouth, MA Inspection Conducted: April 12, 1986 through April 25, 1986 Team Leader: J. Strosnider, Chief, Section 18, DRP, RI Team Members: L. Doerflein, Martin McBride, Senior Project Engineer,RI Resident Inspector, Pilgrim K. Murphy, R. Fuhrmeister Technical Assistant, DRS,RI Reactor Engineer, RI M. Chiramal, Section Chief, AE00 S. Pullani Fire Protection Engineer,

DRS, RI Reviewed By .

 /J/ Strosnider, Chief LProj cts Section 1B, DRP
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Approved By: ! fi. Kistdfl Chief Protects Branch No. 1, DRP l r , 8605280047 860516 PDR ADOCK 05000293 G PDR _ (J

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SUMMARY AND CONCLUSIONS The AIT reviewed three recent operational problems at Pilgrim: 1) the spurious group-one primary containment isolation on April 4 and 12,1986, 2) the failure of the main steam line isolation valves to open after th solations, and 3) recurring pressurization events in the residual heat removal (RHR) syste The team noted that the licensee's problem solving approaches were carefully structured and appeared thorough. In addition, the team drew -~~ the following conclusions for the three areas of concern:

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No root causes for the spurious primary containment isolations on April 4 and 12, 1986 were identified during the. inspection period, despite considerable licensee effort. The team did not identify any weaknesses in the licensee's problem solving approac The failure of the outboard main steam line isolation valves (MSIV) to re-open following the containment isolations on April 4 and 12 was caused by partial or complete mechanical separation of the valve pilot poppets from the MSIV valve stem assemblies. Pilot poppet set screws did not prevent the poppets from unscrewing from the stem assemblie The RHR pressurization events reflect slow leakage (about 0.5 gpm) past a check valve and two motor operated injection valves in the

 "B" RHR loop. Lack of RHR pressure instrumentation and the lack of periodic tests of the RHR injection check valves inhibit a more thorough diagnosis. No apparent RHR valve failure mechanism has been identified as the reason for this leakag The licensee's conduct of the reactor shutdown on April 11 and 12, 1986, was prudent in light of the recurring RHR pressurization event The licensee's root cause evaluations were not completed and corrective actions were not finalized during the AIT inspection. NRC review of these actions should be conducted prior to startup from this outag Based on the AIT review, the first four items in CAL No. 86-10 have been completed. The fifth and final item will be closed when the licensee submits a written report on the three areas of concern to the Regional Administrator and the Administrator authorizes reactor restar . . -

TABLE 5.1 - EVENTS OF THURSDAY APRIL 10, 1986 Plant RHR System Time Conditions Conditions Comments 0246 Started pulling RHR in standby with Reactor rods cross connect open startup between A & B loop begins Pressure at-105 psig provided by keepfull syste Critical 0700 300 psig 11% steam flow 1000 500 psig RHR flow chart in-12% steam flow dication showing pressure rise in RHR pipin psig RHR Hi alarm; 6 alarms First alarm 12% steam flow once every 15 min indicated on RHR flow chart, no log entr >900 psig Reactor at 12% steam flow pressur Turbine Rolling RHR Hi alarm; 4 alarms, once-every 30 min Unit on Line 1500 STA log - indicates look-ing into valve

    '29B leakage 1600    NWE Log (1600 to 2400) -

maintenance is torquing up valve 29B 1800 RHR Hi alarm; 4 alarms, once every 30 min _ .

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Plant RHR System Time Conditions Conditions Comments 2200 No RHR Hi alarms between 2200 and 0200 2400 Reactor near 100's steam flow _

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TABLE 5.2 - EVENTS OF FRIDAY APRIL 11, 1986 Plant RHR System Time Conditions Conditions Comments 0200 RHR flow test Checks opera-bility of all four RHR pumps 0219' RHR Hi alarm First notation of RHR Hi alarm found in control room log 0315 RHR Hi alarm 0336 "B" RHR loop in torus Pressurization cooling mode of RHR pre-vented when loop-open to torus 1115' RHR secured from torus cooling 1158 RHR Hi alarm 1415 RHR Hi alarm; valve Declared LPCI 288 closed,'both loop "B" inoperative MOVs (28B & 24B) no closed 1653 RHR Hi alarm 1710 Initiated a con- Declared an trolled shutdown Unusual Event, steam flow decrease notified NRC rate of 5% per hour 2000 960 psig, steam flow decrease rate increased to 30% per hour 2200. 930 psig, 33% steam flow 2215 RHR Hi alarm Notified NRC

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TABLE 5.3 - EVENTS OF SATURDAY, April 12, 1986 Plant RHR System Time Conditions Conditions Comments 0030 Turbine off line _ _ _ _ Out of run mode 0200 HPCI in recir- Initiate torus cooling culation mode mode of RHR for reactor pressure control 0215 Significant pressure reduction begins 0400 <100 psig 0645 Out of torus cooling RHR loop A placed in shutdown cooling mode 0908 Reactor Secured from

 <212 degrees F   Unusual Event

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Table Summary of Water Leak Test Data Recorded By Inspector April 17, 1986 Approximate Pump Strokes Pressure Between Valves, PSIG Per Minute ~--

- Time  338/68B 688/298 298/28B 28B/ Pumps Comments
~ 1500 0 22 25 65 104
~ 1510 0-20 300-500 290 100 104 5 min after reaching 300
~ 1520 0-20 600-700 575 330 145 10 min after reaching 600 1540 0-20 950 - - -

1606 4-8 950 950 700 185 1715 4.75 975 975 725 375 to 380 RHR Hi Alarm received Note: 4.75 pump strokes per minute is equivalent to ~ gp FIGURE PCIS INITIATION LOGIC FOR CHANNEL A-1 (Typical of Channels A-2, B-1 and B-2)

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 (  NUCt.l AH REGUI.ATORY COMMISSION ATTACHMENT 1
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April 12,1986 CAL No.: 86-10 Docket Nu@ce: 50-293 Bosten Edison Company M/C Nuclear ATTN: Mr. William D. Harrington Senior Vice President, Nuclear 800 Boylston Street Boston, Massachusetts 02199 Gent.lcmen: Subject: Confirmation of Actions to be Taken with Regard to the Pilgrim Plant Events Which Occurred on April 11-12, 1986 Pursuant to our telephone conversation on April 12, 1986 with Mr. Oxsen it is our understanding that you have taken or will take the following actions: Maintain all af fected equipment related to the events which occurred on April 11-12, 1926 in its as-found condition-(except as nu essary to maintain the plant in a r,afe >liutdown t.undition) In order to preserve any evidence which would be needed to inspect or reconstruct the event . Deveinp troubleshooting plans and procedures and provide those to the NRC Augmented Inspection Team (Ali) for their review and comment prior to initiating any troubleshooting of the affected equipmen . Advise the AIT leader prior to the conduct of any troubleshooting ar,tiv itie * Make available to the NRC AII relevant written material related to previous problems with the affected equipmen . Provide a written report to the ftegional Administrator prior to restart that contains your evaluatlon of the following: Intersystem leakage through the motor-operated injection valves (including the check valve) of the residual heat removal system;

      ' The primary containment isolation which occurred daring shutdown af ter the reactor mode switch was repositioned from the run mode to the startup mode; f _

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.. l The failure of the outboard main steam isolation valves' to reopen after resetting the primary containment isolation signa This report should include the underlying causes for the above noted events, an assessment of their relationship to previous events including the events of April 4, 1985, corrective actions taken and your basis for restart, including the criteria used and your analyses associated with these criteri Further we understand that restart will not occur until you receive authoriza-tion from the Regional Administrato If your understanding of the actions to be taken are different than those described above, please contact this of fice within 24 hours of the receipt of this lette Thank you for your cooperatio

Sincerely, . Thomas E. Hurley Regional Administrator cc: L. Oxsen, Vice President, Nuclear Operations C. J. Mathis, Station Manager Joanne Shotwell, Assistant Attorney General Paul Levy, Chairman, Department of Public Utilities Plymouth Board of Selectmen Plymouth Civil Defense Director Senator Edward P. Kirby Public Document Room (PDR) local Public Document Room (LPDR) Nuclear Safety Information Center (MSIC) NRC Resident Inspector Commonwealth of Massachusetts (2)

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A , o ATTACHMENT 2 PERSONS CONTACTED The following is a partial listing of the licensee personnel that were contacted during the inspectio W. Harrington, Senior Vice President, Nuclear L. Oxsen, Vice President, Nuclear Operations (Senior Licensee Manager Present at the Exit Interview) C. Mathis, Nuclear Operations Manager P. Mastrangelo, Chief Operating Engineer K. Roberts, Director Outage Management N. Brosee, Maintenance Section Head T. Sowdon, Radiological Section Head J. Seery, Technical Section Head E. Ziemianski Management Services Section Head S. Wollman, On-Site Safety and Performance Group Leader R. Sherry, Chief Maintenance Engineer E. Graham, Compliance and Administrative Group Leader P. Smith, Chief Technical Engineer W. Clancy, Nuclear Engineer, FS and MC Group Leader T. McLoughlin, Nuclear Operations Sr. Electrical Engineer A. Morisi, Operations Assistant to Director of Outage Management

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o ATTACHMENT 3 Tests / Checks Performed During Mode Switch /PCIS Investigation The licensee performed the following tests / checks of tne PCIS components, including the reactor mode switch. The mode switch testing was performed in all four mode positions under various human factor scenarios i.e., with and without key removed, pulling up or pushing down while turning _ _ the mode switch, et Surveillance Test Procedure 8.M.2-1.5.3.1, 2, 3, and 4 Primary Con-tainment Isolation Logic Channel Test - Channels A-1, A-2, A-3, A-4, respectively Revision 6; performed on April 14, 198 Inspection of contacts of the PCIS relays in Channels A-1, A-2, B-1 and B-2, in accordance with Procedure 3.M.3-8, Inspection / Trouble Shooting - Electrical Circuits, Revision 6, performed on April 14, 1986, along with the above 4 PCIS Logic Test Surveillance Test Procedure 8.M.1-19, Reactor Water Level (RPS/PCIS), Revision 13; performed on April 15, 1986. (While performing this test, an inadvertent closure of the MSIVs and steam line drain valve M0-220-2 occurred)

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Trouble Shooting Procedure for.the investigation of inadvertent closure of MSIVs and M0-220-2 during performance of the above Sur-veillance Test Procedure (8.M.1-19) on April 15, 1986; performed in accordance with procedure 3.M.3-8 on April 15, 198 Surveillance Test Procedure 8.M.2-1.4.4, Main Steam Line Low Pressure, Revision 5, performed on April 16, 198 Trouble Shooting Procedure to check out the AC and DC solenoid circuits of the MSIVs, performed on April 17, 198 Temporary Procedure TP86-59, Mode Switch Test for Steam Line Low Pressure Bypass, Revision 0; performed on April 19, 198 Trouble shooting procedure 3.M.3-8 to check out the effect of vibra-tion on reactor vessel level Yarway level indicating switches; performed on April 21, 198 Trouble shooting procedure 3.M.3-8 to confirm the vibration effect observed during the above test; performed on April 21, 198 Trouble shooting procedure 8.M.1-19 to investigate the cross charnel interaction of relays suspected during the performance of the above two' tests; performed on April 21, 198 O e

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Trouble shooting procedure 3.M.3-8 to investigate the vibration / cross channel interaction observed as the April 21, 1986 testing; performed on April 23, 198 Trouble shooting procedure 3.M.3-8 to check out the contact resis-tances of the relays in the PCIS trip circuitry, performed on April 23, 198 Surveillance test procedure 8.M.2-1.4.3, Main Steam Line High Flow, Revision 1; performed on April 24, 198 Surveillance Test Procedure 8.M.1-12, Main Steam Line High Radiation, Revision 11; performed on April 24, 198 Temporary Procedure TP 86-68, Mode Switch Resistance, Revision 0; performed on April 24, 198 Trouble shooting procedure 3.M.3-8 to check out loose wire in the PCIS circuitry and the RPS grounding connection; performed on April 24, 198 A

o-t O ATTACHMENT 4 DOCUMENTS REVIEWED Plant Design Change Request No. 83-48, "MSIV Refurbishment", dated October 5, 1983 Atwood and Morrill Co. Inc., " Instruction Manual for 20" Main Steam Isolation Valves".

- ~' Procedure No. TP 86-61, "MSIV Plot disassociation Test", Revision 0, dated April 17, 1986 Procedure No. 2.2.92, " Main Steam Line Isolation and Turbine Bypass Valves", Revision 15, dated May 8, 1985 Procedure No. 8.7.4.4, "MSIV Trip", Revision 12, dated January 30, 1986 i }}